<!--
 * @Description: 类选择器
 * @Author: rendc
 * @Date: 2021-08-05 16:26:12
 * @LastEditors: rendc
 * @LastEditTime: 2021-08-05 16:35:27
-->
<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>类选择器</title>
  <style>
    .app {
      width: 60px;
      height: 170px;
      border: 1px solid yellowgreen;
      border-radius: 50%;
    }

    .one {
      background-color: red;
    }

    .two {
      background-color: green;
    }

    .three {
      background-color: orange;
    }

    .circle {
      width: 50px;
      height: 50px;
      border-radius: 50%;
      margin: 5px;
    }
  </style>
</head>

<body>
  <div class="app">
    <div class="one circle"></div>
    <div class="two circle"></div>
    <div class="three circle"></div>
  </div>
</body>

</html>